FRIDAY, March 23, 2018 (HealthDay News) -- Obesity rates have continued to climb significantly among American adults, but the same hasn't held true for children, a new government report finds.

Obesity among adults increased to about 40 percent in 2015-2016, up from 34 percent in 2007-2008, according to the U.S. Centers for Disease Control and Prevention researchers. That means two of every five adults now struggle with obesity.

Meanwhile, about 18.5 percent of kids were obese in 2015-2016, compared with 17 percent in 2007-2008.

"It's a different story for adults than it is for youth," said report author Dr. Craig Hales, a medical epidemiologist with the CDC. "In adults, unfortunately, we see a continuing increasing trend. But in youth, we see over the last 10 years, there has been this flattening out of the obesity and severe obesity prevalence rate."

One weight expert agreed the latest batch of data is mixed.

"There's no doubt about it, overall obesity remains an epidemic in the U.S. The numbers are tremendous," said Dr. Robert Courgi, an endocrinologist with Northwell Health's Southside Hospital in Bay Shore, N.Y. "But I thought I saw a silver lining, that it plateaued in children. Maybe all these community efforts that we've put forth are making a difference."

Obesity is defined as a body mass index (BMI) of 30 or more. BMI is a measurement based on weight and height. The study also found that severe obesity -- a BMI of 40 or more -- had increased during the past decade.

Severe obesity increased from about 6 percent to about 8 percent among adults, but remained at around 5 percent for children, the investigators found.

Hales said the study shows more effort is needed to combat America's obesity epidemic, even among children.

"Ideally, we'd like to see a decreasing trend, but that's not what we're seeing here," Hales explained.

Courgi noted that these results do show that obesity can be addressed, given that it doesn't appear to have been passed on to children.

Efforts such as providing healthier food in schools, promoting physical activity among children, and teaching kids about proper diet and exercise appear to be helping stem obesity in younger Americans, Courgi suggested.

The next step will be to extend that approach to adults on a medical basis, by treating it as a diagnosable disease, he said.

"We still need to change the culture's views on obesity," Courgi added. "Obesity is a disease. If you had an infection, you would take antibiotics. It needs to be recognized as a diagnosis with a solid treatment plan."

Dr. Reshmi Srinath, director of the Weight and Metabolism Management Program at the Icahn School of Medicine at Mount Sinai in New York City, agreed.

"We need to take a multidisciplinary approach to obesity prevention and really focus on increasing awareness of obesity and its associated complications, and start screening for obesity and complications at a young age," Srinath said.

The findings were published online March 23 as a research letter in the Journal of the American Medical Association.